The purpose of this study is to test if low levels of estrogens in the blood stream have an effect on bone density many years after menopause. We published an abstract that showed that the reduction of residual serum estrogen levels in postmenopausal women to near undetectable levels increases bone resorption and results in compensatory decreases of serum PTH. This is the first direct demonstration that even low levels of serum estrogens are important determinates of bone resorption in late postmenopausal women and thus may provide partial protection against the development of osteoporosis. No future studies are planned based on these results at this time.